Some temporal characteristics of the atmospheric radio noise on 27 kHz at the Kuhlungsborn Observatory during the period 1952-83

Thirty-two years of measurements of the atmospheric radio noise on 27 kHz at Kuhlungsborn Observatory are analysed to obtain long-term trends and to test, after the decrease of the noise level during the cooling (1952-67) period, the reproduction and increase in the warming (1968-83) period. Significant trends for the daytime noise level (12.00-16.00 LMT) were observed to be downward between the periods 1954-58 and 1969-73 and upward to 1979-83. The corresponding trends in the nighttime noise level (22.00-02.00 LMT) downward between 1954-8 and 1974-8 and upward until 1979-83 are also significant for most of the months. A seasonal variation was found for the absolute values of the slope of the linear trend of the daytime and nighttime noise level. The monthly differences between the mean noise levels of the warming and cooling periods.